From 56163f69f881fa69fd57e459efc8f8071d53d4db Mon Sep 17 00:00:00 2001
From: pravic <ehysta@gmail.com>
Date: Fri, 9 Jun 2017 22:48:57 +0300
Subject: [PATCH] One more ES5 fix.

---
 src/theme/book.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index 6261895d..151ed640 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -242,7 +242,7 @@ function run_rust_code(code_block) {
         code: text,
     };
 
-    if(text.includes("#![feature")) {
+    if(text.indexOf("#![feature") !== -1) {
         params.version = "nightly";
     }